Pillows on the market today are built in one of several different ways. Firstly, the pillow can be made from a randomly oriented filling material. An example of this construction is a pillow that is composed of randomly oriented polyester fiber-fill. This construction is not limited to a randomly oriented polyester fiber, but can also include, but is not limited to, wool, cotton, or other fibers in which the material fibers are oriented in random orientations. It is also possible to construct a pillow from randomly oriented solid structures. This type of construction is consistent with pillows made from small foam blocks that are randomly dispersed inside the pillow casing. The foam elements can be made from, but not limited to, man-made foams such a poly foam or visco-elastic foam, to various types of natural foams such as latex foam. In addition to the random orientation of the foam elements, additionally the foam elements can consist of different sizes and shapes. It is also possible to mix different foam sizes and shapes inside of a single pillow covering to create an additional level of randomness.
A second type of pillow construction is made with one or more layers of sheet filling materials within a pillow casing. Examples of this type of pillow are layered poly foam pillows in which one or more types, as well as one or more layers of poly foam are stacked upon one another and then encased in a pillow cover. The layer(s) of foam material can be either man made, such as polyfoam or visco-elastic foam, or natural such a latex. In addition, the layers of sheet foam material can be cut into different contours to allow them to better fit into different body crevices or conforming contours. Also, part of this group of pillow construction is when one or more of the sheet foam layers are fabricated to have a non-uniform surface. A top layer of convoluted foam falls into this category. This type of non-uniform foam layers allows for increased airflow as against uniform surface sheet foam layer, and well as a more localized pressure reduction versus a standard sheet foam material. The advantage of the second type of pillow construction, the uniform sheet layer filled pillow, is that this type of pillow has a uniform resilience and will not flatten out. The problem with the sheet foam pillow construction centers around two principle areas. Firstly, the very nature of sheet foam tends to restrict airflow. Additionally, the continuous sheet nature of this style of pillow does not allow spot pressure reduction. For instance, if a sleeper buries the side of their face in the pillow, areas of the face that protrude will be subjected to higher localized pressures due to the underlying sheet cushioning material not allowing for localized pressure reductions. Along these same lines, the ability of a solid layer cushioning material pillow to mold to a sleeper's anatomy is significantly reduced and compromised.
A third type of pillow construction can be formed by the combination of types one and two (hybrid pillow). This type of pillow often encompasses, but is not limited to, a solid foam center surrounded by a randomly oriented fiberfill material. This type of construction has both the advantages and disadvantages of each respective pillow construction.
A fourth type of pillow construction, that is another variation on the third type of hybrid pillow, is constructed of a pocket spring pillow core that is covered by a sheet cushioning layer. The spring core is of a pocket spring construction like that used in pocket spring mattresses but scaled down to fit into a pillow. This type of spring hybrid pillow has the advantage of being more responsive and reactive than other style pillows because of the spring core. Sometimes a random fiber, or cutup foam, cushioning layer is placed over the spring unit to isolate the springs from the sleeper. In other instances, a solid foam sheet cushioning layer is utilized with a spring core to ensure that the springs will not be felt through the cushioning layer. If a random fill fiber or foam covering is used over the spring core, there is a high probability that the spring core of the pillow can become palpable to a sleeper. However, if the spring core is covered in a sheet foam cushioning material, this spring style hybrid pillow tends to also sleep hot. Additionally, spring core pillows tend not to be flexible and foldable, and not conformable to different sleepers different sleeping demands. Basically, this pillow lies flat and does not have the flexible and foldable pillow characteristics that many sleepers desire. The reason the pillow is not flexible is due to the fact that the pockets of the pocket spring are formed with a bond having a plane that is parallel to the central axis of the coil spring. As a result, any attempt to flex the pocket spring is met with resistance as the coil springs contact each other and resist movement. The advantage of the type four hybrid pocket spring core pillow is that the pillow is both responsive and molds to the individual features of a sleeper's head allowing spot pressure reduction. However, because the pillow is constructed of pocket springs that are bonded to one another along an axis that is parallel to the plane of the spring, the springs have very little freedom of movement relative to one another. This lack of spring movement relative to one another is beneficial in a mattress construction where rigidity is important, but are a negative when considering a pillow where flexibility and moldablility are very positive pillow traits. As a result of this type of hybrid pocket spring construction, these pillows are not very flexible or foldable. Consequently, the sleeper must maintain the pillow in a flat plane. At the same time, if the pillow is covered by a random fiber or foam cushion layer, the cushion layer will tend to flatten out and eventually move into an orientation where the sleeper will feel and be exposed to the actual pocket spring core. On the other hand, if the pocket spring core is covered by a sheet foam cushioning layer, the pillow will be even more inflexible while the sheet foam layer impedes airflow and causing the sleeper and pillow to sleep hot. Furthermore, the sheet foam will exhibit a hammock effect and reduce the benefits derived from using a pocket spring core, essentially reducing the moldable, spot pressure reduction, and responsive characteristics that make this pillow construction desirable.
In all of the aforementioned pillow construction methods several benefits and corresponding shortcomings are evident. In the case of type one, the random fiberfill pillow construction, the random orientation of the filling material fibers allows for an airflow to be able to exist within the fiber construction and hence within the pillow. This allows the sleeper to not overheat when sleeping in a single position over a long period of time since air can flow within the pillow structure and around the sleeper's head. At the same time, the random orientation of the fiber filling allows the sleeper to “mold” the pillow to suit their particular needs. However, the randomness of the fibers, in allowing the pillow to easily mold, also makes the pillows resilience, or bounce back, both unpredictable and potentially compromised. This also results in a pillow that tends to “flatten out” over the course of a night's sleep. Many a sleeper will have to “fluff up” the pillow, by manually attempting to re-randomize the fibers, in an attempt to un-flatten the pillow and restore some of the pillow's original resilience. With regards to the type of construction made from small foam blocks that are randomly dispersed inside the pillow casing similar advantages and disadvantages already discussed also occur. The very nature of random orientation of the foam elements makes the pillow unpredictable in terms of resilience and in term of potentially flattening out.